Drill pipe and production tubing for oil and gas wells are typically provided in the form of round steel pipe (commonly referred to as tubulars), typically in sections (or “joints”) about 30 feet in length, with threaded ends for connecting tubulars into a drill string or a production string, depending on the operation being conducted. The term “make-up” is commonly used to refer to the process of connecting tubulars to each other (i.e., “making up” a threaded connection), and the term “break-out” refers to the process of disconnecting tubulars (i.e., “breaking out” a threaded connection). Well drilling and well servicing involve both make-up and break-out functions, for a variety of purposes well known in the field. During make-up operations, sections of drill pipe or production tubing must be transported from a pipe storage rack of some sort to the rig floor for connection to the string already in the well bore. During break-out operations, the pipe sections must be transported from the rig floor to the pipe rack after they have been disconnected from the string.
Apparatus for handling tubulars during such field operations typically feature a hoisting mechanism that receives a section of pipe from a pipe rack (typically horizontal) positioned close to the drilling rig or service rig (as the case may be). The hoisting mechanism then lifts one end of the pipe and moves it laterally toward and above the rig floor, so that it can be engaged by the rig hoist, which moves the pipe into position for connection to the string of pipe in the well bore. This procedure is reversed during break-out operations. As each pipe section is disconnected from the string, it is lifted by the rig hoist, and workers manouever the lower end of the pipe laterally toward the hoisting mechanism of the pipe-handling apparatus. The rig hoist lowers the pipe onto the hoisting mechanism of the pipe-handling apparatus, which in turn moves the pipe laterally away from the rig, while at the same time restoring the pipe to a horizontal orientation, whereupon it is moved to a horizontal storage rack.
The prior art discloses numerous examples of apparatus for handling tubulars and transporting them to and from pipe storage facilities positioned near a drilling rig or service rig. Canadian Patent No. 2,224,638, issued to Handley et al. on Feb. 24, 2004, describes a horizontal pipe storage rack with an elongate pipe cradle having a shallow V-shaped trough for cradling a tubular. With a tubular thus “loaded” on the apparatus, the far end of the pipe cradle (i.e., the end farthest from the rig floor) is moved laterally toward the rig, and by virtue of one of several alternative mechanical arrangements, this lateral movement has the effect of simultaneously raising the inward end of the pipe cradle, and thus the inward end of the tubular, above the rig floor level so that it can be readily engaged by pipe elevators manipulated by rig floor workers.
The reverse procedure is followed when breaking out a drill string or production string. The Handley apparatus also provides means for rotating the pipe cradle about its longitudinal axis when it is lying in the plane of the pipe rack, so that a tubular cradled in the trough of the pipe cradle after being pulled from the well bore will roll out of the trough and into the rack by gravity.
Additional examples of prior art pipe-handling apparatus are disclosed in the following references:                U.S. Pat. No. 2,631,741 (Tucker), issued Mar. 17, 1950        U.S. Pat. No. 2,656,052 (Tucker), issued Oct. 20, 1953        U.S. Pat. No. 3,053,401 (Jinkins, Jr.), issued Sep. 11, 1962        U.S. Pat. No. 3,559,821 (James), issued Feb. 2, 1971        U.S. Pat. No. 3,706,347 (Brown), issued Dec. 19, 1972        U.S. Pat. No. 3,780,883 (Brown), issued Dec. 25, 1973        U.S. Pat. No. 3,792,783 (Brown), issued Feb. 19, 1974        U.S. Pat. No. 4,347,028 (Dugan), issued Aug. 31, 1982        U.S. Pat. No. 2,631,741 (Tucker), issued Jun. 29, 1950        U.S. Pat. No. 4,386,883 (Hogan), issued Jun. 7, 1983        U.S. Pat. No. 4,552,498 (Dysarz), issued Nov. 12, 1985        U.S. Pat. No. 5,122,023 (Mochizuki), issued Jun. 16, 1992        U.S. Pat. No. 6,069,925 (Morgan et al.), issued Jun. 27, 2000        U.S. Pat. No. 6,533,519 (Tolmon et al.), issued Mar. 18, 2003        U.S. patent application Ser. No. 10/279,453 (Eastcott), filed Oct. 23, 2002        Int. Application No. PCT/DE00/03903 (Borgeling), filed Nov. 7, 2000        
Although each of these examples of prior art pipe-handling apparatus may have beneficial operational features, there remains a need for pipe-handling apparatus that can perform the required pipe-handling functions with increased efficiency as compared with prior art apparatus. In addition, there is a need for apparatus that can perform these functions while having less mechanical complexity that the prior art apparatus. The present invention is directed to these needs.